Air pollution is a growing problem in most cities (big and small). The "Daily Dose" aims to disseminate the best available information on air pollution and engage in discussions to better understand the process of air quality management. For more details on the program, please visit http://www.urbanemissions.info

Saturday, August 04, 2012

Air Pollution Worsening Worldwide

Most of the world's population will be subject to degraded
air quality in 2050 if human-made emissions continue as usual. In this
'business-as-usual' scenario, the average world citizen 40 years from
now will experience similar air pollution to that of today's average
East Asian citizen. These conclusions are those of a study published
August 1 in Atmospheric Chemistry and Physics, an Open Access journal of the European Geosciences Union (EGU).

Air pollution is a major health risk that may worsen with increasing
industrial activity. At present, urban outdoor air pollution causes 1.3
million estimated deaths per year worldwide, according to the World
Health Organisation [1].

"Strong actions and further effective legislation are essential to
avoid the drastic deterioration of air quality, which can have severe
effects on human health," concludes the team of scientists, led by
Andrea Pozzer of the Abdus Salam International Centre for Theoretical
Physics in Italy (now at the Max Planck Institute of Chemistry in
Germany), in the new paper.

The researchers studied the impact of human-made emissions on air
quality, assuming past emission trends continue and no additional
climate change and air pollution reduction measures (beyond what is in
place since 2005) are implemented. They point out that, while
pessimistic, the global emissions trends indicate such continuation.

"At present the post-Kyoto climate negotiations are progressing
slowly, and it is unclear how air quality policies will develop
globally," explains co-author Greet Janssens-Maenhout of the European
Commission Joint Research Centre in Italy. "In regions with economic
growth, it might be less effective to implement emission-reduction
measures due to strong growth in activities in particular sectors; in
countries suffering from the economic downturn, implementing expensive
air-quality measures could prove difficult in coming years," she adds.

"We show that further legislation to control and reduce human-made
emissions is needed, in particular for eastern China and northern India,
to avoid hot-spots of elevated air pollution," says Pozzer. Combined
with the fact that these are regions of high population density,
elevated air pollution here would mean that air quality would worsen
significantly for the average world citizen in 2050.

Air pollution would also increase in Europe and North America, but to
a much lesser extent than in Asia, due to the effect of mitigation
policies that have been in place for over two decades.
Pozzer and his colleagues estimated air quality in 2005, 2010, 2025
and 2050 using an atmospheric chemistry model. "The model uses basic
mathematical formulation to predict the meteorology and the chemical
composition of the atmosphere," Pozzer explains. "In practice, it is a
software used to forecast -- or hindcast, for past years -- the status
of the atmosphere at specific times."

The results show that in 2025 and 2050, under the business-as-usual
scenario studied, East Asia will be exposed to high levels of
pollutants, such as nitrogen dioxide, sulphur dioxide and fine
particulate matter (PM2.5) [2]. Northern India and the Arabian Gulf
region, on the other hand, will suffer a marked increase in ozone
levels.

The analysis now published is the first to include all five major air
pollutants know to negatively impact human health: PM2.5, nitrogen
dioxide, sulphur dioxide, ozone, and carbon monoxide. The scientists
considered pollutants released through human activity, as well as those
occurring naturally such as desert dust, sea spray, or volcanic
emissions.

Taking all pollutants into account, eastern China, northern India,
the Middle East, and North Africa are projected to have the world's
poorest air quality in the future. In the latter locations this is due
to a combination of natural desert dust and man-induced ozone. The
effect of anthropogenic pollution emissions are predicted to be most
harmful in East and South Asia, where air pollution is projected to
triple compared to current levels.

The study aimed to compare the influence of human-made emissions on
air quality in different regions, and show how no-further legislation to
reduce emissions can result in drastic deterioration of air quality
worldwide compared to the present day situation.

Notes
[1] World Health Organisation (WHO) 'Air quality and health' fact sheet (September 2011) http://www.who.int/mediacentre/factsheets/fs313/en/index.html
[2] PM2.5 refers to pollutant particles less than 2.5 micrometers in
aerodynamic size, or about a quarter of the size of a cloud droplet.
According to the WHO, "PM affects more people than any other pollutant."
PM2.5 is more dangerous than particulate matter of larger size because
these particles can reach the smallest of airways and interfere with gas
exchange in the lungs.